Final answer:
EAL 4 is recognized as the common benchmark for operating systems and products in the Common Criteria Evaluation Assurance Levels. It provides a balance between cost, assurance, and return on investment, while EAL 5, 6, and 7 offer higher assurance.
Step-by-step explanation:
The Common Criteria Evaluation Assurance Level (EAL) is a part of the Common Criteria international standard (ISO/IEC 15408) for information technology security evaluation. The EAL represents the depth and rigor of an evaluation, determining the trustworthiness of the security features of a product. Among the levels, EAL 4 is considered as the common benchmark for operating systems and products. It is often referred to as the level that is methodically designed, tested, and reviewed. Higher levels, such as EAL 5, EAL 6, and EAL 7, imply an even greater assurance, but EAL 4 is widely recognized as a balance between cost, assurance, and the return on investment.